Drilling, completion, and production of reservoir wells involve measuring various subsurface formation parameters. Companies often measure percentages of oil, water, and gas mixtures contained in representative fluid samples drawn from formations to determine fluid composition or fluid quality. A detailed description of the fluid properties and characteristics is desirable for an accurate modeling of the fluids in the formation and to determine the economic value of pumping from the formation.
Historically, fluid samples were brought to the surface for analysis in a laboratory, but recent developments have facilitated directly measuring fluid properties downhole during a pumping or sampling sequence using downhole fluid analysis (DFA) techniques. In contrast to laboratory analyses or surface wellsite analyses, which may require a relatively extended amount of time to produce results and may result in undesirable phase transitions as well as the loss of key constituents in samples, DFA techniques may be used to perform fluid analysis in situ and to provide analysis results in real-time.
A known technique for determining the characteristics of a formation fluid often involves performing a spectroscopic analysis at a particular wavelength to measure an optical response of the formation fluid indicative of the presence of a molecule. A spectrometer is relatively accurate in determining the fluid properties and characteristics of molecules with relatively low molecular mass. However, determining the fluid properties and characteristics of molecules with relatively higher molecular masses (or molar masses) is significantly more difficult because they are more difficult or impossible to detect and/or differentiate between using known fluid analysis techniques. For example, using a spectrometer to measure fluids having molecules with relatively higher molecular masses (or molar masses) often produces inaccurate and/or invalid results.